How Does SpaceShipOne Work?
Let's start at the heart of the matter: How does the craft work? Read as Matthew Gionta describes what will happen on this historic flight step by step.
HSW: So, how does SpaceShipOne work?
Matthew Gionta: SpaceShipOne is slung underneath the belly of the White Knight aircraft, two aircraft that we've developed from scratch here. The White Knight is a turbofan-powered airplane that carries the SpaceShipOne up to 45 to 50,000 feet so that we can start our space flight from a relatively high position in the atmosphere where the air's already pretty thin. We're through about 85 percent of the Earth's atmosphere already when we go down 45,000 feet. The air is very rarified up at that altitude so it's a great place to start from. From there we drop the spaceship off of the White Knight and it glides for 10 seconds while the pilot sets up, gets the aircraft all trimmed up, ready for the rocket boost and he throws the switch, and the hybrid rocket motor in the SpaceShipOne accelerates the pilot at about two to three times normal gravity. It accelerates at about twice normal gravity forward and the pilot immediately commences a pullout maneuver to approximately vertical -- he's going pretty much straight up.
And the ship continues to accelerate going straight out for a little over a minute. We don't give out the exact numbers -- then someone can reverse engineer.
So we go about one minute straight up and we burn out about 150,000 feet, roughly. The motor stops burning at that point, but now the ship is moving over 2,000 miles per hour, straight out, and so it coasts. From there it coasts up another 150,000 feet roughly, up until it reaches apogee [the point at which SpaceShipOne is farthest from Earth]. Just before it reaches apogee, the pilot flips another switch that drives some pneumatic actuators -- it takes the tail of the aircraft and the back half of the wing and kinda [makes them]... like a jack-knife is probably the way to think of it.
The aircraft is jack-knifed, and that is positioning the craft, or reconfiguring the craft, for the atmospheric re-entry that it's about to experience. And so you've still got that while he's heading up, and so he starts and that takes about 15 seconds for that feather, as we'll call it, the back half of the craft to go up about 65 degrees. And then he goes through apogee all the while he's experiencing pretty close to zero g -- it's real close to zero g [weightlessness] -- from after burnout all the way through apogee.
And then he starts to fall back in, and he falls, he falls along the same parabolic or ballistic trajectory that he would if he were just a rock. If someone threw a rock up there, it'd be the same kind of parabola. He's on a ballistic trajectory and can't do much about it. If the craft starts to fall back into the atmosphere, picking up speed, it reaches just about zero speed at the top and picks up more and more speed. And as it starts falling into the thicker and thicker air, this jack-knife craft presents its whole belly, just like a belly flop straight onto the air flow to give itself a large cross-sectional area that it's trying to drive through the air to decelerate it.
And that slows it down. The pilot experiences between about 5 or 6 g's of deceleration as he comes back into the atmosphere. And he rides that down to about 50,000 feet or so, maybe 60,000 feet, where he flips the switch to turn it back into a normal airplane with a tail and trail it where it's supposed to be. And he dives out of that maneuver and starts flying again like an airplane, like a glider. He is a glider at that point.
And then he glides from there another... about 10 to 15 minutes back to the airport from which we took off at, here in Mojave.
In the next section, we ask Matthew what its like to ride on SpaceShipOne.